Creating a pexe content handler to translate and run pexes.

services/nacl/content_handler_main_nonsfi_pexe.cc

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <fcntl.h>
+
+#include "base/files/file_util.h"
+#include "mojo/application/application_runner_chromium.h"
+#include "mojo/application/content_handler_factory.h"
+#include "mojo/data_pipe_utils/data_pipe_utils.h"
+#include "mojo/message_pump/message_pump_mojo.h"
+#include "mojo/nacl/nonsfi/nexe_launcher_nonsfi.h"
+#include "mojo/public/c/system/main.h"
+#include "mojo/public/cpp/application/application_impl.h"
+#include "services/nacl/pexe_linker.mojom.h"
+#include "services/nacl/pexe_translator.mojom.h"
+
+namespace nacl {
+namespace content_handler {
+namespace {
+
+void WriteStringToHandle(MojoHandle handle, const char* str, uint32_t size) {
+  MojoResult result;
+  result = MojoWriteMessage(handle, str, size, nullptr, 0,
+                            MOJO_WRITE_MESSAGE_FLAG_NONE);
+  if (result != MOJO_RESULT_OK)
+    LOG(FATAL) << "Could not write message to handle";
+}
+
+void ReadStringFromHandle(MojoHandle handle, char* str, uint32_t* size) {
+  MojoResult result;
+  do {
+    result = MojoReadMessage(handle, str, size, nullptr, 0,
+                             MOJO_READ_MESSAGE_FLAG_NONE);
+    if (result == MOJO_RESULT_SHOULD_WAIT) {
+      result = MojoWait(handle,
+                        MOJO_HANDLE_SIGNAL_READABLE,
+                        MOJO_DEADLINE_INDEFINITE,
+                        nullptr);
+      if (result != MOJO_RESULT_OK)
+        LOG(FATAL) << "Error waiting for string";
+    } else {
+      break;
+    }
+  } while (true);
+  if (result != MOJO_RESULT_OK)
+    LOG(FATAL) << "Could not read message from handle";
+  str[*size] = '\0';
+}
+
+}  // namespace anonymous
+
+class PexeContentHandler : public mojo::ApplicationDelegate,
+                           public mojo::ContentHandlerFactory::Delegate {
+ public:
+  PexeContentHandler() : content_handler_factory_(this) {}
+
+ private:
+  // Overridden from ApplicationDelegate:
+  void Initialize(mojo::ApplicationImpl* app) override {
+    app->ConnectToService("mojo:pexe_translator_app", &translator_);

[Mark Seaborn, 2015/10/20 22:28:58]

I'm curious whether this could just be done in RunApplication()?

[Sean Klein, 2015/10/22 21:50:00]

I'm not entirely sure -- the ApplicationImpl pointer is no longer available in
RunApplication, unless it can somehow be acquired from the
InterfaceRequest<mojo::Application>.

+    app->ConnectToService("mojo:pexe_linker_app", &linker_);
+  }
+
+  // Overridden from ApplicationDelegate:
+  bool ConfigureIncomingConnection(
+      mojo::ApplicationConnection* connection) override {
+    connection->AddService(&content_handler_factory_);
+    return true;
+  }
+
+  // Overridden from ContentHandlerFactory::ManagedDelegate:
+  void RunApplication(
+      mojo::InterfaceRequest<mojo::Application> application_request,
+      mojo::URLResponsePtr response) override {
+    // Needed to use Mojo interfaces on this thread.
+    base::MessageLoop loop(mojo::common::MessagePumpMojo::Create());
+    // Acquire the pexe.
+    base::FilePath pexe_file_path =
+        mojo::common::BlockingCopyToNewTempFile(response->body.Pass());
+    if (pexe_file_path.empty()) {
+      LOG(FATAL) << "Could not redirect pexe to temp file";
+    }
+
+    // Translate the pexe into an object file
+    mojo::ScopedMessagePipeHandle parent_compile_pipe;
+    mojo::ScopedMessagePipeHandle child_compile_pipe;
+    if (CreateMessagePipe(nullptr, &parent_compile_pipe, &child_compile_pipe) !=
+        MOJO_RESULT_OK)
+      LOG(FATAL) << "Could not create message pipe to translator";
+    translator_->PexeTranslate(child_compile_pipe.Pass());
+
+    // Write the name of the pexe to the translating service.
+    WriteStringToHandle(parent_compile_pipe.get().value(),
+                        pexe_file_path.value().c_str(),
+                        pexe_file_path.value().size());
+    // Read the name of the output object from the translating service.
+    char obj_file_name[PATH_MAX + 1];
+    uint32_t path_size = sizeof(obj_file_name);
+    ReadStringFromHandle(parent_compile_pipe.get().value(),
+                         obj_file_name, &path_size);
+
+    // Link the object file into a nexe
+    mojo::ScopedMessagePipeHandle parent_link_pipe;
+    mojo::ScopedMessagePipeHandle child_link_pipe;
+    if (CreateMessagePipe(nullptr, &parent_link_pipe, &child_link_pipe) !=
+        MOJO_RESULT_OK)
+      LOG(FATAL) << "Could not create message pipe to linker";
+
+    linker_->PexeLink(child_link_pipe.Pass());
+
+    // Write the name of the object file to the linking service.
+    WriteStringToHandle(parent_link_pipe.get().value(),
+                        obj_file_name,
+                        path_size);
+    // Read the name of the output nexe from the linking service.
+    char nexe_file_name[PATH_MAX + 1];
+    path_size = sizeof(nexe_file_name);
+    ReadStringFromHandle(parent_link_pipe.get().value(),
+                         nexe_file_name, &path_size);
+
+    // Open the nexe file and launch it (with our mojo handle)
+    int nexe_fd = open(nexe_file_name, O_RDONLY);
+    if (unlink(nexe_file_name))
+      LOG(FATAL) << "Could not unlink temporary nexe file";
+    if (nexe_fd < 0)
+      LOG(FATAL) << "Could not open nexe object file";
+
+    // Pass the handle connecting us with mojo_shell to the nexe.
+    MojoHandle handle = application_request.PassMessagePipe().release().value();
+    ::nacl::MojoLaunchNexeNonsfi(nexe_fd, handle);
+  }
+
+ private:
+  mojo::ContentHandlerFactory content_handler_factory_;
+  mojo::nacl::PexeTranslatorPtr translator_;
+  mojo::nacl::PexeLinkerPtr linker_;
+
+  DISALLOW_COPY_AND_ASSIGN(PexeContentHandler);
+};
+
+}  // namespace content_handler
+}  // namespace nacl
+
+MojoResult MojoMain(MojoHandle application_request) {
+  mojo::ApplicationRunnerChromium runner(
+      new nacl::content_handler::PexeContentHandler());
+  return runner.Run(application_request);
+}